Optical coding device

Abstract

An optical encoder including a graduation plate inscribed with a graduation line along a predetermined direction and an optical reader for optically reading the graduation line on the graduation plate in which a corresponding electric signal is outputted from the optical reader in accordance with movement of the graduation plate and the optical reader relative to each other, the optical reader includes a light projecting optical system for irradiating light from a light projecting light source to the graduation plate and a light receiving optical system for focusing light from the graduation plate to a light receiving portion and the light receiving optical system is constituted by a telecentric optical system to thereby enable to be fabricated at low cost by dispensing with high integrating accuracy.

Description

technical field [0001] The present invention relates to an optical encoder, and more particularly to an optical encoder which can be manufactured at low cost without requiring high assembly precision by using a telecentric optical system. Background technique [0002] As is well known, the above-mentioned optical encoder includes: a scale plate marked with scale lines along a set moving direction, and an optical reader for optically reading the scale lines on the scale plate. When the object to be detected moves, the scale plate and the optical reader also relatively move in conjunction with the movement, and at this time, a corresponding electrical signal is output from the optical reader. [0003] The form of the scale plate of the above-mentioned optical encoder differs between a rotary encoder and a linear displacement encoder. In the case of a rotary encoder, a rotary disk is used as the scale plate, and the scale plate and the optical reader are supported so that they...

AI Technical Summary

Problems solved by technology

However, from its detection principle, the distance between the scale lines has to be made small due to the relationship between the laser wavelength, so it cannot correspond to various distances (resolution capabilities)

Moreover, this encoder requires a special scale and lacks versatility

[0014] On the other hand, in the case of using an encoder of a reflective optical reader independently having an optical axis for light projection and an optical axis for light reception, since the two optical axes are inclined symmetrically with respect to the normal line of the scale plate, the scale plate The sharpness and size of the scale line caused by deviation, shaking and tilting also change greatly, which is not suitable for high-precision detection purposes.

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